The interview includes one of those usefully provocative maps: What would a map of the world look like if it were distorted so that the size of every country is relative to its population? The patterns are expected: In North America, Canada shrinks and Mexico grows. In the rest of the world, Russia shrinks and China and India grow. Japan looks a lot larger when weighted by population; Australia looks smaller. Africa appears notably larger than South America. For me, such maps also emphasize that U.S. economic growth over the next few decades is likely to be related to how extensively the American economy participates in the growth that is happening in the rest of the world.

Chamie also points out that the growth rate of world population is slowing dramatically. One of the next main demographic preoccupations will be population aging. Soon, the above-65 elderly in the world population will exceed the number of children for the first time in world history.

"Two thousand years ago, world population was estimated at about 300 million. It reached the first billion mark at the beginning of the 19th century—the estimate is about 1804—when Thomas Jefferson was U.S. president. The second billion mark was reached in 1927. We had a tripling of world population from 1927 to near the end of the 20th century, when it reached 6 billion. We’re now approaching 7 billion people.

Why did that happen? It’s because we had this wonderful thing occur: a decline in mortality rates. This decrease in mortality is humanity’s greatest achievement. Every government wishes to see lower mortality and longer life. The world benefited from modern medicine and public health; antibiotics, of course; also better nutrition, better facilities, better working conditions. What lagged behind were changes in birth rates. This difference between birth rates and death rates gave rise to what is commonly called the population explosion. We reached a peak population growth rate of about 2.1 percent in the late ’60s, and we reached the peak annual increase of about 87 million people in the late ’80s. The latest United Nations projections show a world of about 10.1 billion people by the end of the 21st century. ..."

"While the 20th century was the century of demographic growth (and this growth will continue through the 21st century—we are likely to add 2 to 3 billion people), the world’s population is aging. Very soon, we will see a reversal where the number of children, which has historically been more than the number of people above 65, will become less than the elderly. The aging of the world’s population will be pervasive; it will affect every household. It will affect the economy, social interactions, voting patterns, lifestyles."